Observation of ultrafast free carrier dynamics in single layer MoS2

Antonija Cabo, Jill Miwa, Signe Grønborg, Jonathon Mark Riley, Jens Johannsen, Cephise Cacho, Oliver Alexander, Richard Chapman, Emma Springate, Marco Grioni, Jeppe Lauritsen, Phil King, Philip Hofmann, Søren Ulstrup

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Abstract

The dynamics of excited electrons and holes in single layer (SL) MoS2 have so far been difficult to disentangle from the excitons that dominate the optical response of this material. Here, we use time- and angle-resolved photoemission spectroscopy for an SL of MoS2 on a metallic substrate to directly measure the excited free carriers. This allows us to ascertain a direct quasiparticle band gap of 1.95 eV and determine an ultrafast (50 fs) extraction of excited free carriers via the metal in contact with the SL MoS2. This process is of key importance for optoelectronic applications that rely on separated free carriers rather than excitons.

Original languageEnglish
Pages (from-to)5883–5887
JournalNano Letters
Volume15
Issue number9
Early online date19 Aug 2015
DOIs
Publication statusPublished - 9 Sept 2015

Keywords

  • Transition metal dichalcogenides
  • MoS2
  • Free carriers
  • Exitons
  • Time- and angle-resolved photoemission spectroscopy

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